The heart is an electro-mechanical system performing two major pumping functions. The left side of the heart, including the left atrium and left ventricle, draws oxygenated blood from the lungs and pumps it to various organs of the body to provide the organs with oxygen for their metabolic needs. This pumped blood flow is called cardiac output. The right side of the heart, including the right atrium and right ventricle, draws deoxygenated blood from the organs and pumps it into the lungs where the blood gets oxygenated. The pumping functions are accomplished by contractions of the myocardium (heart muscles). In a normal heart, the sinoatrial node, the heart's natural pacemaker, generates electrical impulses, known as action potentials, which propagate through an electrical conduction system to various regions of the heart to excite myocardial tissues in these regions. Coordinated delays in the propagations of the action potentials in a normal electrical conduction system cause various regions of the heart to contract in synchrony such that the pumping functions are performed efficiently.
A blocked or damaged electrical conduction system causes irregular contractions of the myocardium, a condition generally known as arrhythmia. Arrhythmia reduces the heart's pumping efficiency and hence, diminishes the cardiac output. The diminished cardiac output can also be caused by heart failure, such as when the myocardium is weakened and its contractility is reduced. A heart failure subject usually suffers from both a damaged electrical conduction system and deteriorated myocardium.
Heart failure has been recognized as a significant public health concern with a huge economic impact. Subjects hospitalized with decompensated heart failure reportedly have a high rate of rehospitalization within six months (more than 50% according to some studies), with a significant percentage rehospitalized within a month. Hospital readmission is a principal factor responsible for the cost associated with managing heart failure. Premature hospital discharge and insufficient resolution of heart failure worsening are among the factors contributing to the high rate of rehospitalization. Therefore, there is a need to improve management of heart failure hospitalization for reducing the rate of rehospitalization. In an example, Wariar et al., in U.S. Pat. No. 8,052,611, entitled METHOD AND APPARATUS FOR MANAGEMENT OF HEART FAILURE HOSPITALIZATION, refers generally to a hospitalization management system.